‘This could be embarrassing’ – Wolff on what’s behind Mercedes engine loophole saga

Toto Wolff, the Mercedes team boss, has claimed that rival engine manufacturers have been sending “secret letters to the FIA” over the F1 2026 compression ratio saga over recent months.

And he says efforts to close off the loophole are rooted in fear among rival teams that they could be “embarrassed” by Mercedes on track this season.

Toto Wolff: Mercedes rivals’ lobbying has ‘massively ramped up’

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Mercedes has been named in widespread reports that some engine manufacturers have been exploiting a loophole in the new F1 2026 engine rules related to compression ratios.

It is said that Mercedes has found a way to increase the compression ratio of its power unit to 18.0 when the car is out on track and running hot, as opposed to 16.0 – the maximum compression ratio stated in the regulations – when measured at ambient temperature.

Rival manufacturers have voiced fierce opposition to Mercedes’ engine trick with it emerging last week that they are pushing for a change to the way compression ratios are measured in time for the season-opening Australian Grand Prix next month.

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A resolution to the saga is expected within weeks with the 2026 engines set to be homologated by the FIA on March 1, seven days before the first race in Melbourne.

Wolff has consistently insisted that Mercedes kept the governing body in the loop throughout the development of its F1 2026 engine, telling PlanetF1.com and other media outlets last week that “communication with the FIA was very positive all along.”

Asked if he is surprised by how the engine debate has blown up, Wolff claimed that rival manufacturers have “massively” ramped up efforts to close off the loophole over recent months by holding secret meetings and submitting secret letters to the FIA.

He told PlanetF1.com and other media outlets during Bahrain testing: “I think that the lobbying from the other engine manufacturers has massively ramped up over the last few months.

“Secret meetings, secret letters to the FIA – obviously, there’s no such thing as secret in this sport – and that has brought it to this situation.”

Rumours have persisted for more than a year that Mercedes’ preparations for the 2026 regulation changes were more advanced than its rivals, with the compression ratio saga entering the public domain for the first time last December.

Wolff has claimed that the anticipation surrounding the Mercedes power unit had left other manufacturers in fear of being “embarrassed” in 2026.

He said: “I think everybody was a little bit too excited about the performance of the Mercedes engine powered teams.

“I think that our colleagues from the other brands have been carried away a little bit [with the fear] that this could be embarrassing, which I don’t think it is at all.

“But it’s OK. Let’s see how the test pans out and then God knows what next black swan event is going to come to us.”

Additional reporting by Mat Coch and Thomas Maher

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